The overall objective of this research project remains the isolation of a viral agent from the cultured synovial cells obtained from involved joints of patients with rheumatoid arthritis. Toward this end, a number of studies have been carried out, including the following: (1) to continue efforts aimed at virus isolation from rheumatoid synovial cells (RSC); (2) to identify a specific "neo-antigen" in RSC; (3) to explore the possible cytotoxic activity of rheumatoid sera, lymphocytes, and synovial fluids on Cr51 labeled RSC; (4) to transfer by co-cultivation the trait of hyaluronate synthesis from RSC to cells not producing hyaluronate; (5) to determine if RSC contain an antigen cross-reactive with viral antisera using immunoelectrophoresis; and (6) to examine the possibility of a rabbit model of viral persistence in joints, using adenovirus. BIBLIOGRAPHIC REFERENCES: Hamerman, D.: Evidence for a viral etiology of rheumatoid arthritis. In: The Immunological Basis of Connective Tissue Disorders, 5th Lepetit Colloquium. L.G. Sylvestri, Ed. ASP Biological & Medical Press, Amsterdam, p.17, 1975. Hamerman, D.: Evidence for an infectious etiology of rheumatoid arthritis. Ann. N.Y. Acad. Sciences 256:25, 1975.